1. Field of the Invention
The present invention relates to a battery pack, using a battery comprising one or more cells as a power source and for connecting power to an external host device.
2. Description of the Related Art
A battery pack comprises one or more cells (secondary battery) of a charging type, and it is used as a power source for an electronic device such as portable telephone, notebook-sized personal computer, CD or DVD player, digital camera, etc. In an external host device such as a portable electronic device using a battery pack of this type as the power source, it is essential to facilitate the control and management to identify the condition of the battery pack. In case of trouble, it is necessary to promptly judge how to restore the condition to normal. However, in a battery pack of a conventional type, it has been not possible to fulfill these functions.
To solve the above problems, it is an object of the present invention to provide a battery pack, by which it is possible to control state transition such as a charging/discharging state or a stop state and to monitor information on state transition of the battery pack at the external host device.
To attain the above object, the present invention provides a battery pack, using a battery comprising one or more cell as a power source and for connecting power to an external host device, where said battery pack comprises charging/discharging means connected in series to the battery and for performing charging and discharging, current detecting means for detecting the charging and the discharging current, voltage detecting means for detecting voltage, temperature detecting means for detecting temperature, and control means, whereby the control means is operated in such manner that it is turned from at least one of charging state, discharging state, charging stop state or discharging stop state to another state by controlling the charging/discharging means according to the charging/discharging current, voltage and temperature as detected, and information of said state transition is transmitted to the external host device at least once when there is a request or at regular intervals or when there is state transition.
Further, the charging/discharging means comprises a switch for charging the battery and a switch for discharging the battery. The control means comprises a switch for spare charging, whereby, in a charging state or a discharging state, the switch for charging and the switch for discharging are both turned on. In the charging stop state, the switch for charging is turned off and the switch for discharging is turned on. In the discharge stop state, the switch for charging is turned on and the switch for discharging is turned off, and it comprises a spare charging switch arranged in parallel to the charging switch and the discharging switch and for charging micro current or a very small amount of current. The control means is operated in such a manner that, when the voltage is lower than the preset value, the charging switch and the discharging switch are turned off and only the spare charging switch is turned on, and it is turned to a spare charging state. When the voltage is not higher than the preset voltage value even when charging has been performed with the preset charging current under the spare charging state, the control means turns off the spare charging switch and it is turned to a spare charging stop state. When it has been detected that the connection with the external host device is disconnected, it is turned to system disconnection. The charging switch and the discharging switch are both turned off, and it is turned to a non-operation state.
Also, the control means is operated in such a manner that, when the voltage is compared with the preset value and pulse charging is performed, and when average current in the preset period of time is lower than the preset value, it is turned to a charging stop state and it is defined as a charging stop state based on full charging detection. Also, when the charging switch is turned off and the discharging switch is turned on in the charging temporary stop state, and when this charging temporary state is longer than the preset period of time, it is turned to the charging stop state, and this is defined as a charging stop state based on full charging detection. In the charging stop state based on the full charging detection, it is turned to the charging state under the condition that the charging ratio is lower than the preset value. In the charging state, it is turned to the charging stop state under the condition that the charging current is higher than the preset value, and this state is defined as a charging stop state based on abnormal current. Also, it is turned to the charging stop state under the condition that the cell voltage is lower than the preset value even when the charging time is longer than the preset time, and this state is defined as a charging stop state based on abnormal charging time. Also, in the charging stop state based on the full charging detection, in the charging stop state based on abnormal current, and in the charging stop state based on abnormal charging time, it is turned to discharging state under the condition that discharging has been detected, and it is turned to the non-operation state under the condition that system disconnection has been detected.
Also, the control means is operated in such a manner that, in the charging state, it is turned to a charging stop state tinder the condition that the cell temperature is higher than the preset value, and this state is defined as a charging stop state based on temperature. Also, under the condition that the cell temperature is lower than the preset value, it is turned from the charging stop state based on the temperature to the charging state. In the spare charging state, it is turned to a non-operation state under the condition that the cell voltage is higher than the preset value and system disconnection has been detected. In the discharging state, it is turned to the discharging stop state under the condition that eh cell temperature is higher than the preset value, and this state is defined as a discharging stop state based on abnormal temperature. In the discharging state, it is turned to discharging stop state under the condition that the discharging current is higher than the preset value, and this state is defined as a discharging stop state based on abnormal current.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.